Alternating current voltage regulator



'Fell 4, 1941- J. B. HANsx-:LL 2,230,945

ALTERNATNG CURRENT VOLTAGE REGULATOR Original Filed Nov. 4, 1958 /25 /aTDi/g2. /zof/ 11e-l? max WPS@ 129 1 /25 @my F22 Iza 555 H56 PatentedFeb. 4, 1941 UNITED STATES PATENT ori-ice John Bentley llansell,Pendleton, England, alsignor to General Electric Company, a comration ofNew York Original application November 4, 1938, Serial No.

1939, Serial No. 285,126.

vember 17, 1937 3 Claims.

This invention relates to alternating current voltage regulators andmore particularly to a T-connected three-phase arrangement of two of theregulators forming the subject matter of my original application SerialNo. 238,925, illed No-Y vember 4, 1938, and assigned to the assignee ofthe present application. v

This is a division of my above-identified original application. In thatapplication there is disclosed a moving core type variable voltagetransformer regulator in which a pair of windings are serially connectedacross an input or supply circuit. These windings have separate magneticcircuits, the reluctances of which are oppositely l varied by a commonmovable magnetic core member. Secondary windings are closelyelectromagnetlcally coupled with one or both of the primary windings andare connected to energize a separate output circuit or to boost or buckthe voltage 2 of the input circuit. The changes in the relativereluctance of the magnetic circuits of the primary windings causevariations in voltage induced in the secondary windings by reason of thevaried division of input circuit voltage between the two primarywindings. In this way a relatively wide range oi' voltage adjustment issecured. Any number of these regulators may be inter- 30 connected to asystem of like number of phases so as to secure the adjustment orregulation of the voltage of any polyphase circuit. Asis also disclosedin the above-identified original application, the individual regulatorsmay be operated 35 simultaneously by suitable means or they may becombined into a unitary structure and the windings may be connected inmesh or in star.

In accordance with the present invention a novel and simplifiedarrangement is provided 40 whereby but two of the above-describedsinglephase type regulator units may be connected in equivalentT-formation so as to regulate the voltage of a three-phase circuit in aneconomical manner. s 45 An object of the invention is to provide a newand improved polyphase voltage regulator.

Another object of the invention is to provide a novel and simplearrangement of what consists essentially of two single-phase regulatorsof 5c the basic type disclosed in my above-identiiied originalapplication interconnected in equivalent T-formation so as to regulatethe voltage of a three-phase circuit.

The invention will be better understood from u the following descriptiontaken in connection with Divided and thi! 8W cation July 18, In GreatBritain Nothe accompanying drawing and its scope will be pointed out inthe appended claims.

In the drawing, in which certain of the reference characters correspondto those designating similar elements in my above-identified original 5application, Fig. 1 is a diagrammatic illustration of a simpleequivalent T-connection, Fig. 2 is a vector diagram for illustrating theoperation of Fig. 1, Fig. 3 is a modification which automaticallymaintains the same neutral point for the voltage triangles of both theinput and output circuits of the regulator, and Fig. 4 is a vectordiagram for illustrating the operation of Fig. 3.

Referring now to the drawing, and more particularly to Fig. l, there isshown therein a magnetic core structure consisting of members I and 2having slots a, b, c and d. Movably mountedv between the members I and 2are movable core members I3 and I3 which are mechanically interconnectedat ||2 so as to operate together as 20 a unit. An input circuit IIIA,IIIB, ||IC is connected to a plurality or primary windings I I6, I Il,IIB, |I9, and |2| and a three-phase output circuit IISA, I I5B and II5Cis connected to the input circuit through a plurality of secondarywindings |24', |25, |20, |21, |28 and |29.

The two bottom slots c and d of the fixed cores I' and 2 accommodatebetween them four secf tions of one primary winding, namely the sectionsI I 6 to I I9, inclusive, which sections are connected 30 in series withone another across the input conductors IIIB and IIIC in the mannershown. The two upper slots a and b of the fixed cores each accommodate asingle winding, |20 and I2| respectively, which are connected in serieswith one another between the input conductor IIIA and through aconductor |22, to the junction |23 between the coils ||8 and |19, whichjunction is the mid-point of the winding comprising the coils I|6 to I|9inclusive. The output lead II5A 40 is connected with the conductor IIIAthrough two secondary coils |24 and |25 in series with one another, thecoils |24 and |25 being disposed in the same slots b and a as' theprimary coils |2| and |20 respectively. The coils |24 and |25 45 areconnected in such directions as to produce voltages opposing andassisting respectively the voltagebetween the conductor |`I IA and thejunction point |23. The lead I|5B is connected with the conductor |I|Bthrough two secondary coils |26 and |21 in series with one another, saidcoils being disposed in the same slots d and c as the primary coils IIBand IIS respectively. The lead IHC is connected with the conductor |||Cthrough two secondary coils |28 and |29 in series l5 with one another,the coils |23 and |23 being also disposed in the slots d and c,respectively. The coils |26 and |23 are connected in such direction asto produce voltages opposing the voltage between the conductors IB and|||C, whilst the coils |21 and |29 are connected ln such directions asto assist said voltage between the conductors |||B and |||C.

The operation of the arrangement of Fig. 1 will be clear from the vectordiagram of Fig. 2, in which the vector OA represents the voltage betweenthe junction point |23 and the conductor il'lA, the vectors OB and OCrepresent respectively the voltage from said junction point to theconductor l IB and to the conductor |||C. To these voltages are addedalgebraically the resultant voltages of the coils |24 and |25; |26 and|21; and |28 and |29, as indicated by the vectors AA', BB', and CC'respectively when the voltage of the leads ||5A, ||5B and HSC isincreased with respect to the input voltages at the conductors ||'|A,|||B and |||C, and by the vectors AA", BB" and CC when the voltage ofsaid leads is reduced with respect to said input voltages.

With the arrangements of connections shown in Fig. l, the neutral orcenter point of the voltage triangle on the output leads ||5A, ||5B and||5C does not correspond with that of the voltage triangle on the inputconductors |||A, |||B and |||C, except when the input and outputvoltages are equal, and in some cases this may be considered adisadvantage. Fig. 3 illustrates an arrangement of windings which may beemployed when it is desired that the center of the voltage triangles ofthe input and output circuits shall always coincide. In Fig. 3 thevarious coils are illustrated with their axes parallel with therespective vectors in the vector diagram of Fig. 4. The xed and movingcores of this embodiment of the invention are similar to that of Fig. 1,the xed cores again having four slots a, b, c, d (Fig. l) in which thevarious coils are disposed. The slots c and d again accommodate primarycoils ||8, ||1, H8 and l|9 as in Fig. 1, with corresponding secondarycoils |26, |21, |23 and i29 for increasing the voltage between the leads||5B and HSC with respect to that between the conductors iB and |||C.The ends of the coils |21 and |29 remote from said leads ||5B and ||5Crespectively, are, however, instead of being connected directly withsaid conductor |||B and |||C respectively, connected with the latterthrough secondary coils disposed in the slots a and b so as to introducevoltages in quadrature with the voltages in the coils |26 to |29inclusive. Thus, coil |21 is connected with input conductor |||B throughconductor |3| and secondary coils |32 and |33 respectively disposed inthe slots a and b (Fig. l) said coils |32 and |33 producing voltages inopposition to one another. In similar manner, the coil |29 is connectedwith conductor |||C through a conductor |34 and secondary coils |35 and|36 also disposed respectively in the slots a and b (Fig. l), said coils|35 and |36 producing voltages in opposition to one another. The lead||5A is again connected through the two secondary coils |24 and |25arranged as in Fig. 1, being located in the slots b and a. respectively.

' The primary winding in the slots a and b may comprise two coils as inFig. 1, but the arrangement shown in Fig. 3 includes a further featurein which for providing a neutral point connection, namely at |31 in Fig.3, the coils |20 and |2| of Fig. 1 are each divided into two sections|20 and |20" on the one hand and |2|' and |2|" on the other hand. Thecircuit proceeds from conductor |||A through the two coils |20' and |2|'to the connection |31 and thence ythrough the two coils |20" and I2 tothe junction point |23. By this means the voltage between the conductor|31 and the junction point |23 will always be maintained at apredetermined proportion of the voltage between the conductor |||A andsaid junction point, this proportion being determined by the relativenumber of turns of the coils |20' and |2| on the one hand and the coils|20 and |2|" on the other hand. Consequently, by arranging the coils|20" and |2|" each with half as many turns as each of the coils |20 and|2| the conductor |31 provides a neutral point as will be clear from thevector diagram of Fig. 4, in which the same nomenclature is employed asin Fig. 2, and the potential of the conductor |31 is shown at N, thevector ON being one-third the length of OA. For increasing the outputvoltages with respect to the input voltages the coils |32 and |36produce voltages as represented by the vectors Bf-BQ and C-CQrespectively, which are in quadrature with the vectors OB and OC and areof opposite sense to the vector OA, and these voltages together with thevoltages produced by the coils |21 and |29, represented by the vectorsBQ-B and CQ-C cause resultant voltages in the leads ||5A, ||5B and |I5Cas represented by A', B', C', the neutral of which coincides with thatof the triangle ABC. For decreasing the voltage of the leads ||5A, ||5Band ||5C with respect to the conductors |||A, |||B and |||C, the coils|32 and |33 produce voltages as represented by the vectors BQ and CQrespectively, and together with the voltages produced by the coils |26and |28 (vectors QB" and QC) cause resultant voltages of the leads ||5A,|I5B and ||5C as represented by the triangle A, B", C", the neutral ofwhich is again coincident with that of the triangle ABC.

Although the several arrangements of windings above described are shownas arranged as unitary regulators with two slots for each phase, it willbe appreciated that more than two slots might be provided for eachphase, for example, four slots per phase or said winding arrangementsmight be applied to two separate regulators with their moving corescoupled together. Single phase embodiments of these modifications aredescribed in my above-identified parent application.

It will also be understood that the various winding arrangementshereinbefore indicated in the foregoing description, althoughillustrated diagrammatically as being employed in regulators with thesame general arrangement of cores as in the embodiment shown in myabove-identified parent application, may be employed with any otherequivalent arrangement of magnetic circuit structure and relativelymovable core or cores falling within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An alternating current voltage regulator for a three-phase circuitcomprising a. winding having a mid-tap, a first pair of windings havinga common magnetic circuit connected respectively to the terminals ofsaid mid-tapped winding, said pair of windings and said mid-tappedwinding being serially connected between two of the phase conductors ofsaid three-phase circuit, means for oppositely varying the reluctance ofthe magnetic circuits of said mid-tapped Winding and of said phasecircuit and connected in series with said two phase conductors forsymmetrically varying the voltage of said three-phase circuit.

2. An alternating current voltage regulator for a three-phase circuitcomprising a winding having a mid-tap, a iirst pair of windings having acommon magnetic circuit connected respectively to the terminals of saidmid-tapped winding, said pair of windings and said mid-tapped windingbeing serially connected between two of the phase conductors of saidthree-phase circuit, means for oppositely varying the reluctance of .themagnetic circuits of said mid-tapped winding and oi' said first pair ofwindings, a second pair of windings connected in series between theremaining phase conductor of said three-phase circuit and said mid-tap,means operative simultaneously with the first-mentioned means foroppositely varying the reluctance of the magnetic circuits of thewindings constituting said second pair of windings, a group of threewindings closely electromagnetically coupled respectively to a windingof said second pair and to a winding on each side oi said mid-tap andconnected in series with said phase conductors for symmetrically varyingthe voltage of said three-phase circuit, and at least two additionalwindings closely inductively coupled to at least one of said second pairof windings and connected in series respectively with the two of saidgroup of three windings which are closely inductively coupled to thewindings on opposite sides of said mid-tap for producing quadraturevoltages with respect to the voltages of their serially connectedwindings which are of such value as to prevent a diierence between theneutral of the three-phase input and output voltages of said regulator.

3. An alternating current voltage regulator for a three-phase circuitcomprising a winding having a mid-tap, a first pair of windings having acommon magnetic circuit connected respectively to the terminals of saidmid-tapped winding, said pair of windings and said rnid-tapped windingbeing serially connected between two of the phase conductors of saidthree-phase circuit, means for oppositely varying the reluctance of themagnetic circuits of said mid-tapped winding and of said first pair ofwindings, a second pair of windings connected in series between theremaining phase conductor `of said three-phase circuit and said mid-tap,means operative simultaneously with the rst-mentioned means foroppositely varying the'reluctance of the magnetic circuits of thewindings constituting said second pair of windings, and a group of threewindings closely electromagnetically coupled respectively to a windingof said second pair and to a winding on each side of said mid-tap andconnected respectively in series with said phase conductors forsymmetrically varying the voltage of said three-phase circuit.

JOHN BENTLEY HANSELL.

